Flexible and adaptive processes in speech perception

Abstract

The perception of speech can be flexible, influenced by multiple sources of information, and plastic, tuned over time to cumulative experience. This chapter provides examples of cognitive neuroscience research, presented at a workshop on speech and lexical processing. Section I demonstrates effects of different sources of semantic information on perception and brain activity. Section II presents evidence for the role of internally generated linguistic predictions in guiding adaptive plasticity, and for the potential involvement of a cerebellar-mediated supervised learning mechanism. Finally, Section III examines the relationship between flexibility and adaptive plasticity and underscores the need for considering their underlying neurobiological mechanisms and their interactions with cognitive processes, and other factors that contribute to generalization in order to further elucidate this relationship.The perception of speech depends on mapping a highly variable and complex acoustic signal onto meaningful sounds and words. However, when the speech signal violates learned regularities due to natural, environmental, or synthetic distortions of the speech signal, accurate perception can be maintained through adjustments in mapping the acoustic signal onto more abstract linguistic information. Such adjustments are facilitated by disambiguating contexts that influence perception of the acoustic signal to be more consistent with the context. They can also accumulate, over brief periods of exposure, and affect perception of later instances of the distorted speech (adaptive plasticity). Current cognitive neuroscience research continues to investigate the underlying mechanisms and neural systems that support these flexible and adaptive properties of speech processing.The main goal of this chapter is to review findings presented at a workshop on speech and lexical processing, largely from our research group and collaborators, on studies investigating flexible and adaptive processes in speech perception. Section I of this chapter describes behavioral and functional neuroimaging results that provide evidence for interactions across multiple levels of language

Adaptive Plasticity Under Adverse Listening Conditions is Disrupted in Developmental Dyslexia

“…As reviewed briefly above, speech processing is remarkably dynamic and adjusts rapidly to the mapping of acoustic speech input to linguistically relevant representations in online speech processing (Bertelson, Vroomen, & De Gelder, 2003;Bradlow & Bent, 2008;Idemaru & Holt, 2011;Norris et al, 2003;Samuel & Kraljic, 2009;Schwab et al, 1985;Zhang & Holt, 2018). Although the mechanisms driving these adaptive plasticity effects are still unknown, multiple groups have proposed supervised error-driven learning as a possibility (Guediche, 2017;Guediche et al, 2014;Norris et al, 2003;Vroomen et al, 2007) and at least one study has implicated the cerebellum as a key component of the neurobiological network that is involved (Guediche et al, 2015). Thus, adaptive plasticity may represent another form of procedural learning postulated by Nicolson and Fawcett (2011) to be impaired in developmental dyslexia.…”